Penningroth S M, Witman G B
J Cell Biol. 1978 Dec;79(3):827-32. doi: 10.1083/jcb.79.3.827.
A nonhydrolyzable ATP analog, adenylyl imidodiphosphate (AMP-PNP), has been used to study the role of ATP binding in flagellar motility. Sea urchin sperm of Lytechinus pictus were demembranated, reactivated, and locked in "rigor waves" by a modification of the method of Gibbons and Gibbons (11). Rigor wave sperm relaxed within 2 min after addition of 4 micrometer ATP, and reactivated upon addition of 10-12 micrometer ATP. The beat frequency of the reactivated sperm varied with ATP concentration according to Michaelis-Menten kinetics ("Km" = 0.24 mM; "Vmax" = 44 Hz) and was competitively inhibited by AMP-PNP (Ki" approximately to 8.1 mM). Rigor wave sperm were completely relaxed (straightened) within 2 min by AMP-PNP at concentrations of 2-4 mM. The possibilities that relaxation in AMP-PNP was a result of ATP contamination, AMP-PNP hydrolysis, or lowering of the free Mg++ concentration were conclusively ruled out. The results suggest that dynein cross-bridge release is dependent upon ATP binding but not hydrolysis.
一种不可水解的ATP类似物,腺苷酰亚胺二磷酸(AMP-PNP),已被用于研究ATP结合在鞭毛运动中的作用。通过对吉本斯和吉本斯(11)方法的改进,对美西刺海胆精子进行去膜、重新激活,并使其锁定在“僵直波”状态。在加入4微摩尔ATP后,僵直波精子在2分钟内松弛,并在加入10 - 12微摩尔ATP后重新激活。重新激活的精子的摆动频率根据米氏动力学随ATP浓度变化(“Km” = 0.24毫摩尔;“Vmax” = 44赫兹),并被AMP-PNP竞争性抑制(“Ki ”约为8.1毫摩尔)。在浓度为2 - 4毫摩尔的AMP-PNP作用下,僵直波精子在2分钟内完全松弛(伸直)。AMP-PNP导致松弛是由于ATP污染、AMP-PNP水解或游离Mg++浓度降低的可能性被完全排除。结果表明,动力蛋白横桥的释放依赖于ATP结合而非水解。